Rock drilling auger apparatus



Oct. 22, 1968 R. W. MILLER 3,406,768

ROCK DRILLING AUGER APPARATUS Filed Sept. 9, 1966 4 Sheets-Sheet 1INVENTOR R OBERT W. MILLER ATTORNEYS.

Oct. 22, 1968 R. w. MILLER 3,405,768

ROCK DRILLING AUGER APPARATUS Filed Sept. 9, 1966 4 Sheets-Sheet 2INVENTOR.

ROBERT W. MILLER ATTORNEYS.

R. W. MILLER ROCK DRILLING AUGER APPARATUS Oct. 22, 1968 4 Sheets-Sheet5 Filed Sept. 9, 1966 LINE 4701 0 A3 5 5m zorzEwzwm I0 INVENTOR.

ROBERT W. MILLER IOO IOOO LOAD/INCH OF BORE (lb/m) ATTOR Oct. 22, 1968 wM R 3,406,768

ROCK DRILLING AUGER APPARATUS Filed Sept. 9, 1966 4 Sheets-Sheet 4-INVENTORY ROBERT w. MILLER ATTORNEY.

United States Patent 3,406,768 ROQK DRILLING AUGER APPARATUS Robert W.Miller, Cincinnati, Ohio, assignor to Alaskaug, Inc., Cincinnati, Ohio,a corporation of Ohio Continuation-in-part of application Ser. No.370,997, May 28, 1964. This application Sept. 9, 1966, Ser. No. 594,639

4 Claims. (Cl. 175-162) ABSTRACT OF THE DISCLOSURE This inventionrelates to the art of drilling rock and is particularly concerned withdrilling rock, concrete or other difiicultly penetrable surfacesimbedded in the earths surface. The invention is concerned specificallywith an apparatus and method for drilling into such surfaces Withstepped augers of the general type described in the patent to Henning2,731,237 dated Jan. 17, 1956, in which substantial down pressure isexerted on the auger from above and the auger rotated to bore into therock in a series of circular concentric paths at levels corresponding tothe placement of the individual bits on the steps of the auger. Thisapplication is a continuationin-part of my application, Ser. No.370,997, filed May 28, 1964, now abandoned.

Briefly described, the apparatus of my invention may be described ascomprising a fixed base or frame, an

auger mounted in said frame, the auger having cutting bits spirallyarranged in steps, means for rotating said auger, means mounted on saidframe for exerting a unidirectional force from said frame along the axisof said auger, and means for superimposing on said auger an additionalforce in periodic pulses.

The invention may also be described as providing means for modifying aunidirectional force as by permitting the force to build up, suddenlyrelieving it, and immediately reapplying it.

The novel method may be briefly described as comprising rotating astepped auger on its axis under a unidirectional force or pressure alongits axis and simultaneously superimposing an increased force or pressurealong its said axis in periodic pulses. The method may also be viewed ascomprising loading a stepped auger bit unsteadily with a load or downpressure which, on a time average basis, is equivalent to the maximumsteady load.

In the art of oil drilling it has heretofore been suggested to providemeans for longitudinally vibrating a rotating drill rod within the wellhole. Various means and mechanisms have been devised for this purpose,and elaborate theories have been advanced for the apparent increasedefficacy of an oil drilling rig provided with such means. Thisprocedure, however, has always been accomplished by hanging the drillstring in the well hole and placing the power generator for producingthe desired virbrations within the well hole. The drill string is ineflfect rattled up and down in the well hole and periodically knocksagainst the rock, much like a hand-operated star drill. Moreover, thetype of holes bored with such apparatus are generally relatively small,9" in diameter or less, and the effect of such longitudinal vibration(sometimes termed oscillatory percussion) has been confined to the workthat these relatively small drill bits do within this restricted area.

According to the present invention drilling of relatively large holes isaccomplished with a stepped auger with a unidirectional pressuregenerated positively from a fixed foundation and exerted directly alongthe vertical axis of the bit. The means for exerting pressure down uponor along the axis of the bit is secured to a fixed framework firmly setinto or onto the surface of the earth from which the drillingoperationis begun and thus provides a firm base upon which and withinwhich to absorb the reactive forces generated during the drillingoperation.

I have found that the effectiveness of drilling into various rockformations with a stepped auger upon which a steady down pressure isexerted can be increased many fold by the periodic superimposition ofadditional pressure pulses on said auger. The optimum amount ofsuperimposed pressure and the frequency thereof will of course dependupon the type of rock in which the boring is to be made, the speed ofthe drill, the power applied thereto, and the limitations of thehydraulic or other load-applying system. I have found, however, thatwith large stepped angers of 24" and 36" diameter and larger, thesuperimposition of pulses of additional pressure on an auger alreadysubject to a steady pressure greatly increases the efiicacy of the bitswhich tend to break the rock inwardly and away from the different landsformed during stepped auger drilling and results in a marked increase inthe rate of penetration over that which can be accomplished by applyinga steady down pressure alone.

I have found that the secondary pulses applied are advantageously of agreater magnitude than those forces applied by the steady pressure.

I have also found that the frequency of these pulses is advantageouslymaintained relatively low, of the order of 30 to 60 per minute. At afrequency of per minute the efiicacy of unsteady loading falls offrapidly and is almost indistinguishable from steady loading.

With a portable rig I have found that in drilling with steady pressurewithin the capability of the system, there is a tendency for the rig tojump or chatter due to the impact of the bits spinning and cutting inthe rock. Surprisingly, this chatter is obviated when an additionalpressure is pulsed into the system. Accordingly, the invention permitsthe achievement, with relatively light portable equipment, penetrationrates which are typical of much heavier equipment, and increased rateswhere heavier and more rugged equipment is used.

A principal object of the invention is to provide a means for and methodof greatly increasing the rate of penetration at which the augerdrilling of rock and similar material can be accomplished.

A further major object is to provide a means and method by which suchincreased rates can be achieved with relatively light, portableequipment.

The novel features that are considered characteristic of the inventionare set forth in the appended claims. The invention itself, however,both as to its organization and method of operation, together withadditional objects and advantages thereof, will be understood from thefollowing description of a specific embodiment when read in conjunctionwith the accompanying drawing in which:

FIG. 1 is a side elevation with certain parts shown diagrammatically ofa portable drill rig embodying the invention, designed to borevertically oriented holes;

. FIG. 2 is a side elevation showing a stepped auger of the type to beused with such a rig to accomplish the purposes of the invention;

FIG. 3 is a perspective view of a vertically bored hole partiallydrilled in the rock showing the stepped down crater formed when drillingrock with a stepped auger and in which the rock is cut away to form aremainder of narrow ledges;

FIG. 4 is a schematic view of an alternative way in which the hydraulicsystem may be connected in order to provide a high flow rate to load thehydraulic cylinder;

FIG. 5 is a chart showing the results of drilling tests on Indianalimestone in which unsteady loading in accordance with the invention wascompared with steady loading; and

FIG. 6 is a diagrammatic view of an alternative way in which thehydraulic system may be connected.

Referring to the drawings, a drill rig comprising a frame 10 may beconventionally mounted on wheels 11. Secured rearwardly of the frame ofthe rig is a heavy and massive mounting 12 comprising a topmost arm 13in which is supported a hydraulic cylinder 14. Depending from the bottomof the cylinder is a piston rod 15 to which is secured a thrust bearing16 arranged to exert a downward vertical thrust against bearing 17 towhich is attached a Kelly bar 18. Kelly bar 18 is journaled forlongitudinal and rotary movement in a suitable bearing in the lower arm19 of the mounting. Below this bearing is a gear box 20 arranged toimpart rotary movement to the torque bar of the stepped auger 21, shownonly diagrammatically in FIG. 1, but illustrated in perspective in FIG.2. Power is supplied to gear box 20 through shaft 22 by motor 23 whichmay be suitably supplied with power from motor generator set 24.Conventional jacks 25 are provided in order to provide a firm base fromwhich the drilling operation can proceed.

In the illustrative embodiment of FIG. 1 hydraulic pressure is appliedto cylinder 14 through a primary system comprising a pump 30, highpressure line 31, control 32, feed line 33, return lines 34 and 35, tothe low side 38 of pump 30. A second hydraulic pump 40 feeds highpressure fluid through line 41 through solenoid operated valve 42 intoline 31. Return line 35 to the low side 38 of pump is intermediatelyconnected to the low side 36 of the secondary pump 40 and the low sidesof each pump are interconnected through conduit 37. In the illustrativeembodiment the pumps 30 and 40 provide three gallons per minute at 2000pounds per square inch and may be actuated by five horsepower motors,

In order to produce an intermittent superimposed pressure upon theprimary system I provide a motor 43, having a shaft to which is secureda cam 44 operating through a suitable cam follower on connecting rod 45secured to a switch 46 in electric circuit 47, 48 connected to solenoidvalve 42. The switch 46 is pivoted to open and close the circuit and toenergize and deenergize the solenoid valve 42. By varying the speed ofthe motor 43 I can vary the rate at which valve 42 opens and closes.When it opens it opens the secondary system into the primary system andcontrols the frequency of the pulses superimposed upon the primarysystem. I have found that variations of between 30-60 cycles per minuteare advantageous for most rock drilling, the precise frequency beingdependent upon one or more of the known variables that must be reckonedwith in this field of endeavor.

An alternative hydraulic hook-up is disclosed in FIG. 4 in which pumps30a and 40a are ganged together to provide a high flow rate to loadcylinder 14a. The various parts of the system are similar to thosedepicted in FIG. 1 but are designated with the reference letter a.Variable relief valves R may be provided as well as a suitable checkvalve C and pressure gages G in order to more effectively control thesystem.

A second alternative system is shown in simplified form in FIG. 6, inwhich the various parts of the system described in connection with FIG.4 are distinguished by the letter b. In this arrangement I use a singlehydraulic pump 30b and insert an accumulator 50 in the high pressureside of the system. The pump 30b charges the accumulator 50 whichestablishes a predetermined hydraulic pressure for the system. Solenoidvalve 42b suddenly and periodically relieves the pressure andimmediately reapplies it when the cam 44b operates switch 46b toenergize and deenergize valve 42b. Hydraulic fluid under pressure isthus supplied to cylinder 14b and the pressure is periodically relievedwhen the solenoid valve 42b operates to close the hydraulic circuit. Thehydraulic fluid returns to the pump through reservoir 36b.

An illustrative stepped auger which can be advantageously used with myinvention is of the type shown in detail in FIG. 2, comprising a torquebar 21a, a spiral auger flight or flange 21b provided with steps uponwhich are mounted a series of carbide bits 210, at different radialdistances from the center line of the auger and in different horizontalplanes. The bits, mounted securely in the steps of the auger by meanswhich are not a part of the present invention, present a steppedattitude to the rock and after drilling is commenced, produces a seriesof annular steps in the bottom of the hole as shown in FIGS. 1 and 3,comprising lands A, B and C.

An example of my process was carried out on massive dolomite with a 36"auger rotating at 20 r.p.m. with a steady down pressure of 4000 lbs. onthe primary system. With this set-up I achieved a penetration of aboutper minute. When additional pressure of 8000 lbs. was introduced intothe secondary system 41, 42, in pulses at a frequency of 200 cycles perminute, the rate of penetration was increased to 2 per minute-or morethan a five-fold increase. Later tests showed that the frequency of 200per minute could have been decreased considerably.

I have found that steady pressure of four tons can be effectivelysupplemented by pulses as high as eight to twelve tons in order toachieve greatly increased rates of penetration.

In tests conducted with the apparatus of the invention on Indianalimestone, using a 24" two-flight auger, the penetration in inches perrevolution was measured against the load in pounds per inch of bore.These tests were carried out for both steady and unsteady (pulsating)loading, using the same time-average equivalent loading. The resultswere recorded and plotted on log-log paper as shown in FIG. 5. As willbe noted, substantial increased penetration was obtained for the sameload per inch of bore by utilizing the principles of the presentinvention.

I am unable to determine the precise physical explanation of thesephenomena but I believe that the marked increase in penetration isobtained by the chipping of the rock inwardly from the lands in largeirregular areas designated X in FIG. 3, which reduces materially theremaining area upon which the cutting bits work. These chips are quicklythrown up onto the auger flange and brought up to the surface in thespoil.

It should be understood that the illustrative embodiment showingvertical drilling is not intended to limit my invention since equivalentforces can be generated in horizontal or intermediate planes.

Having thus described my invention, I claim:

1. A rock drilling apparatus comprising in combination, a frame, anauger mounted on said frame, and having a helical flange, drill bitssecured to the lower portions of said flange at varying distances fromthe axis and in different horizontal planes, means for rotating saidauger about said axis, means for disposing said auger with its axisextending substantially normal to the rock formation to be drilled,means for applying a steady load to said auger along said axis so thatthe bits bite into said rock in concentric circular paths as the augeris rotated and is pressed thereagainst by said steady load, and meansoperable upon said steady loading means to modify said steady load tovary the pressure exerted against said rock intermittently in pulses,whereby the rock is removed in annular steps coincident with theposition of said bits, and irregular areas are simultaneously chippedfrom said steps and removed by the auger flange as spoil, thereby aidingthe effectiveness of the drilling operation and increasing the rate atwhich it is accomplished.

2. The apparatus of claim 1 in which the time-average load generated bysaid modifying means is less than the weight of the entire apparatus.

3. The apparatus of claim 1 in which the pulsing rate is maintained atfrom to cycles per minute.

4. The apparatus of claim 1 in which the magnitude of the pulses issubstantially greater than the magnitude of said steady load.

6 References Cited UNITED STATES PATENTS 12/1937 Johansen l56 X 12/1937Basgan -56 10/1941 Edwards et al 17556 X 5/1951 Bodine 175-56 X 3/1954Bodine 175-56 1/1956 Henning 175-391 4/1956 Zublin l75-56 6/1957 Sewell175-422 10/1958 Putt 173-150 X 6/1960 Bodine 175-55 CHARLES E. OCONNELL,Primary Examiner.

R. E. FAVREAU, Assistant Examiner.

